The basal hypothalamus of Coturnix quail contains gonadotrophin releasing factor (GRF) activity (Follett, 1970) but the precise location of the neurons producing the neurohormone(s) is unknown. Lesioning studies show that the destruction of either of two sites blocks photo-inducible testicular growth. One of these lies in the dorsal basal hypothalamus around the paraventricular organ and the other directly above the median eminence (Sharp & Follett, 1969). These two areas are morphologically distinct when considered either in terms of the distribution of monoamines (Sharp & Follett, 1968) or of tanycyte processes (Sharp, 1972). To explore this problem further, pituitaries were taken from sexually mature quail and fragments of the cephalic lobes were implanted into the hypothalami of gonadectomized birds. By removing the negative feedback effect of gonadal steroids it was hoped to stimulate GRF activity. It was anticipated that, as in rats (Halász, Pupp & Uhlarik, 1962), implanted pituitary cells would